The occlusion of a blood vessel, such as chronic total occlusion (CTO), may occur due to a blockage in the blood vessel. Medical devices used for treating such an occlusion include, for example, a catheter that removes a blockage in a vessel. Patent Document 1 discloses a traditional catheter that includes a blockage-removing element in which two or more wires are interwoven so as to expand or contract in a radial direction for the purpose of removing the blockage in the vessel.
Patent Document 2 discloses a catheter having a mesh-like self-expandable area. The catheter of Patent Document 2 includes a cover (a protective film) at the proximal end part of the self-expandable area, the cover serving as a funnel for guiding or directing a blood flow into a lumen of the catheter. The cover may be formed directly on the mesh by means of adhesive bonding, welding, coating or the like, or may be attached to the mesh with a mechanical fastening device.
Further, the catheter of Patent Document 2 may be used to capture a retrograde guide wire inserted from the opposite side of a blockage in a blood vessel.
Patent Document 1: Japanese Patent No. 3655920
Patent Document 2: Japanese Patent Application Laid-Open No. 2011-517424
However, the catheter of Patent Document 1 removes the blockage by scraping the blockage with two or more expanded wires. The blockage is then inserted into the catheter through a narrow distal end of the catheter. Thus, much of the blockage is left behind in the patient, resulting in a poor blockage-removing efficiency for the catheter.
When capturing a retrograde guide wire, the blockage-removing element of Patent Document 1 expands to raise the wires. While the blockage-removing element is expanded, the retrograde guide wire is inserted through the mesh of the blockage-removing element. Then, the blockage-removing element contracts so that the blockage-removing element constrains the retrograde guide wire with the two or more wires. Therefore, the retrograde guide wire may be inadvertently bent by the blockage-removing element. Accordingly, the catheter of Patent Document 1 may result in an increased risk of breakage.
The catheter of Patent Document 2 may not expand and/or contract the mesh smoothly because there is no degree of freedom in the movement of the cover relative to the mesh.